What is this? PH1600: Introductory Astronomy Lecture 22: In the Beginning …

PH1600: Introductory Astronomy Lecture 21: The Beginning of Our Universe Study: Chapter 19 in The Cosmos book Next Lecture: Chapter 19: Early Forces & Inflation School: Michigan Technological University Professor: Robert Nemiroff Book: The Cosmos by Pasachoff & Filippenko Online Course WebCT pages: This class can be taken online ONLY, class attendance is not required!

You are responsible for…  Reading the book One chapter per “quiz period” Anything from that chapter can appear on quizzes or tests, even if I never mention them during my lecture(s) This quiz period covers Chapters 18  APODs posted during the semester APOD review every week during lecture  Completing the Quizzes Chapter 1, 2, 4, 6, 7, 8, 10, 11, 13, 14, 15 & 18 quizzes already due Chapter 19 quiz due next See WebCT at for detailshttp://courses.mtu.edu/

Universe Beginning: Steady State of Big Bang?  Steady State Universe Perfect cosmological Principle: universe does not evolve with time  Big Bang Universe Universe evolves in time Cosmological Principle: universe looks the same from every location

Microwave Background Radiation  Penzias & Wilson try to map Galaxy radio emission with horn shaped antenna  Find strange hiss in all directions  Can’t eliminate it Not warm pigeon poop  Can’t explain it

Horn Antenna used by Penzias and Wilson to detect the cosmic microwave background radiation.

Microwave Background Radiation  Photons from when the universe was only 400,000 years old  Originally 3000 K, now only 2.7 K  Show that Earth is moving with respect to CMBR  Spot distribution shows universe is 70% dark energy, 13.7 billion years old

CMBR Dipole: Speeding Through the Universe Credit: DMR, COBE, NASA, Four-Year Sky Map APOD: 2006 October 8

COBE All-Sky Map Credit: COBE Project, DMR, NASA APOD: 2006 October 7

Antarctica Hears Little Normal Matter in the Big Bang Credit & Copyright: DASI, CARA, NSF APOD: 2001 May 1

The Race to Reveal Our Universe Credit: BOOMERANG Project, NSF APOD: 2000 May 9

WMAP Resolves the Universe Credit: WMAP Science Team, NASA APOD: 2005 September 25

The Big Bang  t< seconds  Planck epoch  Before Planck epoch, the general relativity description of spacetime breaks down.  No one knows what happens before seconds

The Big Bang: Energy Everywhere  < t < seconds  Universe expands and cools  < T < Kelvin  Radiation epoch All particles have speed near light  Nuclei not stable Broken apart soon after forming

The Big Bang: Particles Freeze Out  < t < 1 second  Universe expands and cools  < T < Kelvin  Protons, neutrons, electrons, positrons now frozen in All particles have speed near light  Nuclei not stable Broken apart soon after forming

The Big Bang: Nuclei Freeze Out  1 < t < 100 seconds  Universe expands and cools  < T < Kelvin  Nuclei become stable  Primordial nucleosynthesis Determines what nuclei remain in the universe Universe mostly hydrogen & helium

The Big Bang: Nuclei Become Atoms  t = 400,000 years  Universe expands and cools  T = 3000 Kelvin  Recombination Atoms become stable Nuclei able to retain electrons  Photons fly free for first time Still flying – form microwave background radiation today

The Big Bang: Formation of Stars and Galaxies  400,000 < t < 4,000,000 years  Dark Ages  Stars not yet formed  4 million years < t < 13.7 billion years  Stars form, galaxies form  Universe cools to 3.7 Kelvin

Inflating the Universe Credit: WMAP Science Team, NASA APOD: 2006 March 23

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The Big Bang: Epochs  Radiation dominated Photon-like energy most abundant t < 300,000 years  Except for brief inflationary epoch  Matter dominated Atoms, molecules, dark matter most abundant 300,000 < t < 5 billion years  Dark energy dominated Now (barely)

The Hubble Deep Field Credit: R. Williams, The HDF Team (STScI), NASA APOD: 2002 September 1

The Andromeda Deep Field Credit: T. M. Brown (STScI) et al., ESA, NASA APOD: 2003 May 19

HUDF: Dawn of the Galaxies Credit: R. Windhorst (ASU), H. Yan (SSC, Caltech), et al., ESA, NASA APOD: 2004 September 29